not neccessary, I had that happened to me couple of time w/ nothing else install, other than RX-34_2007SE_3.2007.10-7_PR_COMBINED_MR0_ARM.bin
The only changed I made was setup my wifi and adding RSS feed. After I go grab the rss, the system crash and went into continuous reboot.

This may or may not help, but what I found out was that if I have dualboot, and boot into another OS, it will work, so it's definitely not the kernel issue, because they shared the same kernel, what I did found out also is that, if I run
"fsck.ext2 /dev/mmcblk0 -f", there seem to be something corrupted in the filesystem. If I continue rebooting, it get worse. The last time I check there isn't any fsck.jffs2, so if the jffs2 fs got corrupt, then there is noway to fix it other than reflash. which to me look a lot like what happened and cause the system to be in reboot loop.